发表机构
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究提出在HL-LHC通过长寿命带电粒子的延迟轻子信号，利用共享耦合条件确定的味比区分中微子质量序，约25个事例即可实现3σ区分，且不依赖CP相位δ_CP。
AI 中文摘要
中微子质量序仍未确定，因为长基线振荡测量与未知的CP相位δ_CP纠缠在一起；无此简并性的对撞机探测将提供定性不同的互补检验。我们证明，当在高亮度大型强子对撞机（HL-LHC）产生 displaced-lepton（ displaced lepton，延迟轻子）信号的长寿命带电粒子同时也是负责马约拉纳中微子质量的媒介子时——即“共享耦合条件”——卡萨什-伊瓦拉（Casas-Ibarra）参数化仅通过庞特科沃-牧-中川-坂田（PMNS）混合参数确定延迟轻子的轻子味比N_e/N_μ。在由此产生的“共享耦合类”模型中，该比值由振荡数据确定，与超出标准模型的所有质量和耦合参数无关，仅受带电轻子味违反数据约束的可计算修正影响，对于正常质量序，N_e/N_μ=0.140；对于倒质量序，该比值为2.11，两种预测相差一个数量级以上。该预测在 Scotogenic 模型、III型跷跷板机制、逆跷跷板机制、线性跷跷板机制以及轻子门户暗物质模型中均成立，且对振荡参数不确定性和探测器效率变化具有稳定性，因为这些因素在比值计算中相互抵消。单一经效率校正的决策准则可区分质量序，结合精确泊松检验的明确事例产额估计表明，仅需约25个延迟轻子事例，借助CMS和ATLAS正在建设的计时基础设施，即可实现3σ区分——因此，长寿命粒子信号的确认将同时确定质量序，且不依赖于δ_CP。
英文摘要
The neutrino mass ordering remains unresolved because long-baseline oscillation measurements are entangled with the unknown CP phase $δ_{CP}$; a collider probe free of this degeneracy would provide a qualitatively different, complementary test. We show that when the long-lived charged particle producing a displaced-lepton signal at the High-Luminosity LHC is also the mediator responsible for Majorana neutrino masses---the \textit{shared-coupling condition}---the Casas--Ibarra parametrization determines the lepton flavor ratio $N_e/N_μ$ of time-delayed leptons in terms of Pontecorvo--Maki--Nakagawa--Sakata (PMNS) mixing parameters alone. Within the resulting \textit{shared-coupling class} of models the ratio is fixed by oscillation data, independent of all beyond-Standard-Model mass and coupling parameters up to calculable corrections bounded by charged-lepton-flavor-violation data, yielding $N_e/N_μ= 0.140$ for the Normal and $2.11$ for the Inverted Hierarchy---a separation of more than an order of magnitude between the two predictions. This prediction holds identically across the Scotogenic model, the Type-III seesaw, the inverse and linear seesaw, and lepton-portal dark matter, and is stable against oscillation-parameter uncertainties and detector-efficiency variations, which cancel in the ratio. A single efficiency-corrected decision criterion identifies the hierarchy, and explicit signal-yield estimates combined with an exact Poisson test show that $\mathcal{O}(25)$ displaced-lepton events suffice for a $3σ$ discrimination with the timing infrastructure already under construction at CMS and ATLAS---so that a positive long-lived-particle signal would simultaneously resolve the mass ordering, with no dependence on $δ_{CP}$.
Comments9 pages, 3 figures, this paper is accepted by Chinese Phys. C
